The Congress for Cultural Freedom is widely considered one of the CIA’s more daring and effective Cold War covert operations. It published literary and political journals such as Encounter, hosted dozens of conferences bringing together some of the most eminent Western thinkers, and even did what it could to help intellectuals behind the Iron Curtain.

The intelligence expert Brian Crozier, who has died aged 94 after a long illness, was the ultimate cold-war warrior: a political vigilante who unashamedly cultivated a close, mutually beneficial, relationship with MI6, MI5 and the CIA, successfully courted Margaret Thatcher and Ronald Reagan, and praised the dictators Pinochet and Franco. He lectured army officers about the risks of a Marxist-Leninist takeover of the ruling Labour party in the 1970s. On one occasion, after telling a group of officers about the potential need for a military coup, the audience, in his words, “rose as one man, cheering and clapping for fully five minutes”.

In the 1960s, at MI6’s suggestion, Crozier was approached by the Congress for Cultural Freedom, a CIA-funded agency that financed publications around the world, including Encounter magazine in Britain. In 1966, with the help of CIA funds, he set up a British-based agency, Forum World Features, and later founded the Institute for the Study of Conflict. He also contributed to the Foreign and Commonwealth Office’s Information Research Department (IRD), a shady organisation whose unattributable reports distributed to susceptible journalists and MPs were designed to highlight the dangers of communist subversion. The IRD was disbanded by David Owen soon after he was appointed foreign secretary in 1977.

That year, continuing in his role of what British intelligence agencies call “an alongsider”, Crozier set up a new group, “The 61”. Its aim was to make up for what he perceived as the failure of western governments to counter communist Soviet propaganda effectively. A former senior MI6 officer, Nicholas Elliott, was one of its fundraisers.

Among Crozier’s friends was Charles Elwell, MI5’s head of counter-subversion until 1981, who instructed his officers to monitor the activities of trade union leaders, as well as the National Council for Civil Liberties and the Campaign for Nuclear Disarmament. So, too, was Stephen Hastings, a Tory MP with whose help he set up the Shield Committee, designed to combat subversion, a phenomenon Crozier described as the “political equivalent of Aids”. He presented a further proposal for a “Counter-Subversion Agency” at a meeting in the City in the summer of 1978, chaired by Thatcher and attended by Sir Keith Joseph, Willie Whitelaw, Lord Carrington and Harry Sporborg of Hambros bank (who had been deputy head of the wartime Special Operations Executive). Thatcher suggested the new agency should be attached to No 10, but Carrington vetoed the plan.